title: A group of low molecular weight (<30 kDa) antigens of heat-killed Mycobacterium tuberculosis H37Rv confer better protection against experimental tuberculosis in guinea pigs.
abstract: Heat-killed Mycobacterium tuberculosis (Mtb) H37Rv-derived antigens were purified by electroelution, and their efficacy was evaluated in conferring protection against Tb in guinea pigs in order to identify those protein antigens as a subunit vaccine. A total sonicate extract of Mtb H37Rv (MTSE) was prepared by growing bacteria on Lowenstein-Jensen (LJ) solid medium to its mid-log phase, harvested, and subjected to ultrasonication. Fractions of MTSE were resolved on 10% polyacrylamide gel electrophoresis into as high (HMW, >60 kDa), middle (MMW, 31-59 kDa), and low molecular weight (LMW, <30 kDa) antigens and were purified by electroelution. The protection efficacy of each purified fraction was assessed in a placebo-controlled study by injecting them separately into a group of two animals. After two booster doses, animals were challenged on day 84, and autopsy of all animals was performed on day 126. On autopsy, animals were scored for formation of tubercles in lungs and their dissemination to organs such as spleen, liver, kidney, and lymph nodes. Viable counts (determined as colony forming unit or CFU) of lung and spleen from each animal were performed on LJ solid medium. Results of this study show that CFU of animals that received LMW antigens were significantly low with respect to control animals when compared to MMW and HMW. In conclusion, LMW of Mtb has greater potential in prevention of tubercle formation and thus could be viewed as a possible vaccine candidate in designing alternative subunit vaccines.
authors.affiliation: Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Trivandrum, India. mkk@sctimst.ac.in
authors.forename: Muralidhar K
authors.initials: MK
authors.lastname: Katti
authors.forename: V
authors.initials: V
authors.lastname: Chall
authors.forename: B
authors.initials: B
authors.lastname: Mahadevan
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D006168:Guinea Pigs; D008970:Molecular Weight; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control*
chemical_list: D000942:Antigens, Bacterial